Charge imbalance waves and nonequilibrium dynamics near a superconducting phase-slip center

Abstract

Using a generalized two-fluid picture to describe a quasi-one-dimensional superconductor near To we provide a heuristic derivation for a set of equations governing the temporal and spatial evolution of the charge imbalance (or branch imbalance) in the quasiparticles. We show that these equations are isomorphic to those that describe a simple electrical transmission line, so that charge imbalance waves may propagate in the superconductor in analogy with electrical signals that propagate down the transmission line. We propose as a model for a phase-slip center in a superconducting filament a localized Josephson oscillator coupled to the transmission line. Applying standard transmission-line theory to solve the problem, we show that the Josephson oscillations in the center generate charge imbalance waves that propagate out to a frequency-dependent distance of the order of the quasiparticle diffusion length A(~. = (Dro.)l/2before they damp out. The time-averaged behavior of the model reduces to the earlier model of Skocpol, Beasley, and Tinkham. A novel consequence of the model is a prediction of intrinsic hysteresis in the dc current-voltage relation. The model also provides a convenient framework for dealing with ac effects in phase-slip centers, including resonance and synchronization in systems of closely spaced phase-slip centers and microbridges.

Charge-imbalance fluctuations in superconductors

“…Note that RQ* is in series with, and independent of, the familiar tunnel oxide resistance, which we call R 0 x for clarity. 6 , and this is the first supporting experimental evidence. …”

Temperature dependence measurements of the supercurrent-phase relationship in niobium nanobridges

“…This could thus be another explanation for the similarity of the critical currents of the bridges near the crossover. Based on theory, phase slippage in the structure results in both intrinsic 27 and thermal hysteresis 28,29 in the IV characteristics of a superconducting nanobridge. In practice, this means that, in order to obtain electronic components with nonhysteretic IV characteristics, the nature of the CPR should be single valued.…”

Resistance anomalies in superconducting mesoscopic Al structures

“…Refinements of the SBT model have been proposed by Kadin et al, 26 by Ivlev and Kopnin 27,28 and by Baratoff. 29 Kadin et al have found that propagating waves of charge imbalance can be excited at the PSC and identified an intrinsic mechanism of hysteresis in the V(I) characteristics.…”